The present invention relates generally to barcode scanners and, more particularly, to a barcode scanning system capable of both receiving and transmitting information.
Numerous optical scanners have been developed for tracking and maintaining information by reading barcode symbols appearing on a label or the surface of an article. The typical one-dimensional (1-D) barcode symbol is a coded pattern of indicia comprised of rectangular shaped bars of various widths spaced apart from one another. The bars and spaces have different light-reflecting characteristics and are used to represent desired information (e.g., price, identity, etc.) regarding an item. A two-dimensional (2-D) barcode provides more complex lines and spaces in two orthogonal axes and represents even more information regarding an item than is represented by 1-D barcodes.
Various systems exist to read barcodes, including hand-held wands, portable laser scanners, and stationary optical reading systems. These systems electro-optically convert the graphical data on the barcode into electrical signals, which are then transformed to alpha-numeric characters to decode the information represented therein. Such characters are generally multiple digit representations and have typically been used as an input to a data processing system for applications in tracking, checkout or sales purposes, fixed asset inventory control, and the like. For instance, parcel delivery companies such as Federal Express and the United Parcel Service (UPS) make large use of barcode scanners. These organizations ship millions of parcels every day. A personal tracking number is usually assigned to each parcel. Barcode scanners are utilized to keep track of an individual parcel (which has a barcode label attached) as it progresses through the delivery process.
One limitation of scanning systems of the past, however, is that they are only capable of receiving information. That is, to date barcode scanners and the like have only been used to read information encoded on barcode labels.
One embodiment of the present invention provides an improved barcode scanning device that retains the same functionality as a normal barcode scanner in terms of reading information on a barcode label but that is also able to transmit information through a barcode to a receiving device connected to a central processing unit (CPU).
According to one aspect of the present invention, there is provided a conventional barcode symbol reading apparatus comprising a photo-emitter, such as a laser diode, and mechanical scanning means such as a rotating mirror for producing a scan line of light along a barcode. In a departure from barcode scanners of the past, however, the present barcode symbol reading apparatus may also include input means for receiving an information signal, an oscillator to produce a carrier signal, and a modulator to modulate the information signal on the carrier signal at a defined frequency. A laser diode in the barcode symbol reading apparatus converts the modulated electrical signal to a light signal, which may then pass through a lens, through the barcode, and to a receiving device connected to a CPU.
In addition to transmitting the modulated information signal through the barcode to the receiving device, the barcode symbol reading apparatus may also read the information encoded on the barcode by illuminating the coded surface and detecting the variations in contrasts of the bars and spaces. Light reflected from the barcode may be collected with a photodetector in a receiving portion of the barcode symbol reading apparatus to produce signals which are amplified and supplied to a low-pass filter. The low-pass filter removes the higher-frequency components of the reflected light signal, such as the information signal. Electronic decoding means may be arranged to receive the low-pass filtered reflected beam and to recover from this portion of the reflected signal the information which was encoded within the indicia on the barcode.
The barcode itself comprises a scannable area of parallel bars and spaces in a manner well known in the art. The barcode may be affixed to one side of a light pipe, such that when the light signal from the barcode symbol reading apparatus illuminates the surface of the barcode, light from the barcode symbol reading apparatus is transported through the light pipe. A sensor coupled to the other end of the light pipe detects the presence of this light. The light, including the modulated information signal and also the lower frequency modulation signal produced by the different levels of translucency of the barcode itself are converted by a sensor to an analog electrical signal which may be supplied to an amplifier and then filtered to remove the low frequency modulation.
In one embodiment of the present invention, the amplifier may supply the electrical signal to a high-pass filter which removes the lower frequency signal modulation. The remaining information signal may then be supplied to an asynchronous decoder in the receiving device, which signal may be converted into framed data and subsequently supplied to a central processing unit (and/or stored in memory).